Price per kilo
You learn to work out what 1 kilo costs when you know the price of more kilos.
How to work it out
- Put the number of kilos and the price under each other in the table.
- Divide both by the number of kilos: then you are at 1 kilo.
- Read under the 1 what 1 kilo costs.
3
1
7,5
2,5
A worked example
4 kg costs £10.00. What does 1 kg cost?
- Divide the number of kilos by 4: 4 ÷ 4 = 1.
- Divide the price by 4 too: 10 ÷ 4 = 2.50.
- 1 kg costs £2.50.
4
1
1000
250
More examples
3 kg costs £7.50. What does 1 kg cost?
- Divide the number of kilos by 3: 3 ÷ 3 = 1.
- Divide the price by 3 too: 7.50 ÷ 3 = 2.50.
- 1 kg costs £2.50.
3
1
750
250
5 kg costs £7.25. What does 1 kg cost?
- Divide the number of kilos by 5: 5 ÷ 5 = 1.
- Divide the price by 5 too: 7.25 ÷ 5 = 1.45.
- 1 kg costs £1.45.
5
1
725
145
Watch out
You multiply instead of dividing: 3 × 7.50.
1 kg is less than 3 kg, so it should be cheaper. Divide the price.
You divide the number of kilos by the price: 3 ÷ 7.50.
You are looking for pounds, so start with the pounds: the price divided by the number of kilos.
Tips
- Check by working back: 3 × 2.50 = 7.50.
Why it works
If 3 kg together cost £7.50, every kilo costs the same. Sharing fairly is dividing, so divide the price by the number of kilos. With the price for 1 kg you can compare prices afterwards.